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A208485
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Number of (n+1) X 2 0..3 arrays with the number of clockwise edge increases in every 2 X 2 subblock equal to the number of counterclockwise edge increases.
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1
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152, 1448, 13800, 131528, 1253608, 11948296, 113880744, 1085412040, 10345202024, 98601453704, 939783162408, 8957194434632, 85372174507240, 813693197494792, 7755414729341352, 73917857257827784, 704520623625326696
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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Empirical: a(n) = 11*a(n-1) - 14*a(n-2).
Empirical g.f.: 8*x*(19 - 28*x) / (1 - 11*x + 14*x^2). - Colin Barker, Jul 03 2018
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EXAMPLE
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Some solutions for n=4:
..3..2....2..3....1..1....3..1....1..0....1..1....2..1....2..0....1..0....1..3
..3..2....0..1....2..2....3..1....2..1....3..1....1..0....3..1....0..0....2..0
..1..3....2..0....1..1....3..3....1..2....0..2....3..1....2..0....0..3....0..2
..0..1....0..1....0..0....3..1....1..1....1..0....0..2....3..1....1..0....2..1
..0..0....3..0....0..0....1..1....0..0....2..1....0..0....1..2....1..0....1..0
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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